Many engines utilize a throttle valve to control or throttle air flow to the engine in accordance with a demand on the engine. Such throttle valves may be used, for example, in throttle bodies of fuel injected engine systems. Many such throttle valves include a valve head carried on a shaft that is rotated to change the orientation of the valve head relative to fluid flow in a passage, to vary the flow rate of the fluid in and through the passage. In some applications, the throttle valve is rotated between an idle position, associated with low speed and low load engine operation, and a wide open or fully open position, associated with high speed and/or high load engine operation. The idle position of the throttle valve may be set by a stop carried by the throttle body. Although the stop may be adjusted prior to use of the throttle body, for example during an initial calibration, it is not movable during use of the throttle body and thus, has only a single position in use of the throttle body.